Heretofore the standard method of constructing ceiling panels with perforate face panels and imperforate back panels has been to bend an L-shaped lip along both end margins and one side margin of both panels, with the foot of the face panel wider than the foot of the back panel, and to crimp the outer margin of the face panel lip around the outer edge of the foot of the back panel lip to form a projecting ledge approximately centered between the face and back panel. On the remaining side, the back panel lip has extended to the level of the upper surface of the face panel, and has been bent to form an upwardly opening channel with its bottom surface flush against a portion of the top surface of the face panel. The face panel has had a marginal lip bent up along a channel-defining outer wall of the back panel lip and crimped over the top edge of the outer wall to form a joint. The projecting ledge of a contiguous panel extended over the space provided by the open-topped channel. At the ends of the panel, the projecting seam rested on an upright wall of a grid-type ceiling support.
This prior art construction had at least two disadvantages. Along the sides, the superposition of the unperforated back panel lip forming the channel along one side interferes with the sound absorption function of the perforations and is visible when the panel is in place in the ceiling, which detracts from the appearance of the ceiling. At the ends, there is no positive interengagement between the grid member and the panel.
One of the objects of the present invention is to provide a construction in which the perforations of the face panels of contiguous ceiling panels are unobstructed and extend to the very margins at which the panels meet.
Another object is to provide a construction in which the panels have a positive engagement with the grid members supporting them, in such a way as to inhibit accidental dislodgment and to ensure a close fit between the contiguous side wall and the grid member.
Another object is to provide a construction in which the panels interengage with one another so as to inhibit unwanted seperation and accidental dislodgement.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.